This invention relates to registers, such as flip-flops, shift registers and the like, and more specifically to various magnetic registers that are non-volatile.
Non-volatile registers are data storage circuits which retain stored information in the absence of power. Current non-volatile registers use flash memory cells to accomplish data storage in a non-volatile fashion. One problem with the use of flash memory cells is the fact that the accompanying memories in devices such as computers and the like are formed from different types of memory cells, e.g. magnetic random access memory (MRAM) cells and the like. Using different types of memory cells results in a requirement for different fabrication processes, which can substantially increase the complexity of the manufacturing process and, thereby, greatly increase the cost.
A type of magnetic register has been proposed, which uses spin dependent magnetic tunneling memory cells (see for example, U.S. Pat. No. 6,021,065, entitled xe2x80x9cSpin Dependent Tunneling Memoryxe2x80x9d, issued Feb. 1, 2000). Generally, these types of devices suffer from metastablity problems. Also, the magnetic tunnel junctions are operated in the major magnetic loop, which makes them slow and the programming requires relatively high currents.
The present invention also contemplates the fabrication of non-volatile shift registers and, to date, no non-volatile shift registers have been proposed. Thus, no prior art for non-volatile shift registers is known at this time.
Accordingly it is highly desirable to provide non-volatile registers which overcome these problems.